1. Field of the Invention
The present invention relates to a video data compression apparatus for compressing and coding noncompressed video data and a method of same.
2. Description of the Related Art
When compressing and coding noncompressed digital video data in units of GOPs (groups of pictures) comprised of an I picture (intra-coded picture), a B picture (bi-directionally predictive coded picture), and a P picture (predictive coded picture) by a method such as the MPEG (Moving Picture Experts Group) and recording the same on a recording medium such as a magneto-optical disc (MO disc) or transmitting the same via communication line, it is necessary to control the amount of data (amount of bits) of the compressed video data after the compression and coding to be not more than the recording capacity of the recording medium or not more than the transmission capacity of the communication line while holding the quality of the image after expansion and decoding high.
For this purpose, first, there is adopted a method of preliminarily compressing and coding the noncompressed video data to estimate the amount of data after the compression and coding (first pass), then adjusting the compression rate based on the estimated amount of data and performing the compression and coding so that the amount of data after the compression and coding becomes not more than the recording capacity of the recording medium by (second pass) (hereinafter, such a compression and coding method will be also referred to as “two pass encoding”).
However, if performing the compression and coding by the two pass encoding, it is necessary to apply similar compression and coding processing two times with respect to the same noncompressed video data, so a long time is taken. Further, since the final compressed video data cannot be calculated by one compression and coding processing, the shot video data cannot be compressed, coded, recorded, or transmitted in real time as it is.